A 2-year observational study has revealed that patients with relapsing–remitting multiple sclerosis (MS) who consume high levels of sodium have increased risk of disease exacerbation. Farez and colleagues estimated dietary sodium intake via urine samples from 70 patients with MS, and found a positive correlation between salt consumption and disease activity. A high-salt diet also increased the risk of developing new MRI-visible lesions. These effects remained robust after controlling for factors such as age and vitamin D levels, and were replicated in a separate group of 52 patients.